rpc: add external_signer option to createwallet

Author: Sjors

src/rpc/client.cpp

@@ -183,6 +183,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "createwallet", 4, "avoid_reuse"},
     { "createwallet", 5, "descriptors"},
     { "createwallet", 6, "load_on_startup"},
+    { "createwallet", 7, "external_signer"},
     { "loadwallet", 1, "load_on_startup"},
     { "unloadwallet", 1, "load_on_startup"},
     { "getnodeaddresses", 0, "count"},

src/wallet/rpcwallet.cpp

@@ -2726,6 +2726,7 @@ static RPCHelpMan createwallet()
             {"avoid_reuse", RPCArg::Type::BOOL, /* default */ "false", "Keep track of coin reuse, and treat dirty and clean coins differently with privacy considerations in mind."},
             {"descriptors", RPCArg::Type::BOOL, /* default */ "false", "Create a native descriptor wallet. The wallet will use descriptors internally to handle address creation"},
             {"load_on_startup", RPCArg::Type::BOOL, /* default */ "null", "Save wallet name to persistent settings and load on startup. True to add wallet to startup list, false to remove, null to leave unchanged."},
+            {"external_signer", RPCArg::Type::BOOL, /* default */ "false", "Use an external signer such as a hardware wallet. Requires -signer to be configured. Wallet creation will fail if keys cannot be fetched. Requires disable_private_keys and descriptors set to true."},
         },
         RPCResult{
             RPCResult::Type::OBJ, "", "",
@@ -2770,6 +2771,13 @@ static RPCHelpMan createwallet()
         flags |= WALLET_FLAG_DESCRIPTORS;
         warnings.emplace_back(Untranslated("Wallet is an experimental descriptor wallet"));
     }
+    if (!request.params[7].isNull() && request.params[7].get_bool()) {
+#ifdef ENABLE_EXTERNAL_SIGNER
+        flags |= WALLET_FLAG_EXTERNAL_SIGNER;
+#else
+        throw JSONRPCError(RPC_WALLET_ERROR, "Configure with --enable-external-signer to use this");
+#endif
+    }
 
 #ifndef USE_BDB
     if (!(flags & WALLET_FLAG_DESCRIPTORS)) {

test/functional/test_framework/test_node.py

@@ -678,10 +678,10 @@ def __init__(self, rpc, cli=False, descriptors=False):
     def __getattr__(self, name):
         return getattr(self.rpc, name)
 
-    def createwallet(self, wallet_name, disable_private_keys=None, blank=None, passphrase='', avoid_reuse=None, descriptors=None, load_on_startup=None):
+    def createwallet(self, wallet_name, disable_private_keys=None, blank=None, passphrase='', avoid_reuse=None, descriptors=None, load_on_startup=None, external_signer=None):
         if descriptors is None:
             descriptors = self.descriptors
-        return self.__getattr__('createwallet')(wallet_name, disable_private_keys, blank, passphrase, avoid_reuse, descriptors, load_on_startup)
+        return self.__getattr__('createwallet')(wallet_name, disable_private_keys, blank, passphrase, avoid_reuse, descriptors, load_on_startup, external_signer)
 
     def importprivkey(self, privkey, label=None, rescan=None):
         wallet_info = self.getwalletinfo()

test/functional/wallet_signer.py

@@ -70,8 +70,15 @@ def run_test(self):
         )
         self.clear_mock_result(self.nodes[1])
 
-        # Create new wallets with private keys disabled:
-        self.nodes[1].createwallet(wallet_name='hww', disable_private_keys=True, descriptors=True)
+        # Create new wallets for an external signer.
+        # disable_private_keys and descriptors must be true:
+        assert_raises_rpc_error(-4, "Private keys must be disabled when using an external signer", self.nodes[1].createwallet, wallet_name='not_hww', disable_private_keys=False, descriptors=True, external_signer=True)
+        if self.is_bdb_compiled():
+            assert_raises_rpc_error(-4, "Descriptor support must be enabled when using an external signer", self.nodes[1].createwallet, wallet_name='not_hww', disable_private_keys=True, descriptors=False, external_signer=True)
+        else:
+            assert_raises_rpc_error(-4, "Compiled without bdb support (required for legacy wallets)", self.nodes[1].createwallet, wallet_name='not_hww', disable_private_keys=True, descriptors=False, external_signer=True)
+
+        self.nodes[1].createwallet(wallet_name='hww', disable_private_keys=True, descriptors=True, external_signer=True)
         hww = self.nodes[1].get_wallet_rpc('hww')
 
         result = hww.enumeratesigners()